Translation:If the fruit were not sweet we would not eat them
After six months still not fixed! The more complex the expressions become, the number of errors increases. I take it as an opportunity to repeat the Swahili phrase another time.
I can't see in the app when you wrote that comment, but I am writing on 14 March 2018 and these errors still aren't fixed. I dutifully report them all too. If only we knew what would help the course developers. (Maybe they are overwhelmed by the sheer number of people reporting the same things. Maybe they are still correcting lesson 4?)
My swahili is failing me a bit on this lesson. Is the "would not have" really correct in these cases? I would have expected "we would not eat them". What gives it the past meaning in these cases?
Right. I think one formal English translation could be: "Were the fruit not tasty, we would not eat it." But I don't speak that way in casual conversation. Thinking about it kind of gives me a headache, but I think I might say: "If the fruit wasn't tasty, we wouldn't eat it."
The past meaning in the case is just Duolingo's error. I believe you are correct in your expectation.
The 'ya' here is the object marker. So it is the "them (the fruits)" in "we would not have eaten them". Words that start with ma- like matunda (fruits) use the -ya- object marker.
And if it had been a single piece of fruit, the object marker would be -li-: tusingelila (we would not have eaten it).